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Offline SteamNut  
#1 Posted : 12 April 2015 17:02:08(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
I understand the risks using old transformers but has anyone damaged their loks when going in reverse when using them? It appears to me more people have more problems on digital layouts when they have a voltage spike then on analog.
Offline Mark_1602  
#2 Posted : 12 April 2015 17:17:18(UTC)
Mark_1602

Luxembourg   
Joined: 24/09/2014(UTC)
Posts: 704
Location: Luxembourg
Hi,

I bought a 66470 transformer a few years ago because I also want to test digital locomotives in analogue mode just to check if everything works fine. Before that I used to do that on an old blue transformer, and I guess that I was lucky, but I wouldn't do it again.

According to what I've read in MRR forums, the risk is higher if you hold the dial in the reverse position for longer. Some people claim that the risk of killing the decoder is real, whereas others say that they've never suffered any damage. Why risk it if you can buy a safe 66470 transformer second-hand without spending a lot of money? I still have a blue transformer that I used in my childhood, but I'd only use it with analogue locomotives.

Best regards,
Mark
Best regards, Mark

I like Märklin items produced in the 1960s or early '70s, but also digital locos & current rolling stock.
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Offline mike c  
#3 Posted : 12 April 2015 23:05:33(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 7,880
Location: Montreal, QC
The oldest of the blue transformers with metal housing were designed that to activate the reverse pulse, you had to push down on the throttle. This meant that the reverse pulse could be activated while the throttle was on. On the more recent blue transformers, this was changed so that the reverse pulse was activated only when the throttle was turned to the left of the zero (off) position.
There is a risk to the new digital decoders when used with transformers where the reverse pulse can be activated while the train was moving.

The other and more significant risk has to do with changes in voltage and the resulting effect that those changes have had on the voltage output of the transformers. For example, in North America, the transformers were built to operate between 110 and 120 (nominal) 117VAC and were designed for max. output of 16VAC and 23VAC reverse pulse. Using those transformers with the current system (nominal 120VAC) increases the output by a few volts, which can be fatal to a modern decoder.
In other places, the line voltage has changed from 240VAC to 230VAC or from 220VAC to 230VAC. In countries like UK, where the mains dropped from 240VAC to 230VAC, this can mean that the old blue transformers no longer can generate a sufficient reverse pulse required to activate the direction change and this will cause older analog locomotives to shoot off at excessive speed. In Germany and elsewhere in Europe where the mains went from 220VAC to 230VAC, this means that the output voltage has gone from 16VAC to around 18-19VAC and the reverse pulse has gone from 23VAC to over 25VAC.

For these reasons, it is recommended to replace older transformers with newer ones designed to provide the correct output for safe operation. European safety norms now require that voltage sparing requirements be met and this has forced Maerklin to introduce new DC based power supplies (for digital). This means that the analog transformer might be coming to the end of it's days.

Regards

Mike C
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Offline H0  
#4 Posted : 12 April 2015 23:40:01(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: mike c Go to Quoted Post
In Germany and elsewhere in Europe where the mains went from 220VAC to 230VAC, this means that the output voltage has gone from 16VAC to around 18-19VAC and the reverse pulse has gone from 23VAC to over 25VAC.
Increasing the input voltage of a transformer by 5 % will increase the output voltage by 5 %.
From 16 V AC to 16.8 V AC, from 23 V AC to 24.15 V AC.


The original question was whether decoders have been fried by blue transformers.
I only have hear-say. Several fora users admitted that they fried decoders with blue transformers.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline baggio  
#5 Posted : 13 April 2015 03:06:11(UTC)
baggio

Canada   
Joined: 21/09/2012(UTC)
Posts: 1,729
Location: Toronto
On the one hand, what Mike said is obviously true:"Why risk it if you can buy a safe 66470 transformer second-hand without spending a lot of money? "

On the other hand, when you buy a used trafo you do not know what's inside unless you look AND you know what you are looking for.

I still remember that in this forum a couple of years ago one poster indicated that he had acquired a whole bunch of blue transformers. The cases made it look as if each one was in tip top shape or almost. He then opened each one up and many (if not all) were in bad to terrible conditions and could easily have started a fire.

If you must run expensive digital locos in analogue, buy either a brand new white trafo or a used one where you know for a fact that what is inside is in excellent conditions.

I have a light blue transformer, Ontario Hydro certified and do not foresee any problems with it BUT once I ran a digital Marklin My World loco, brand new, I reversed it, the loco went back without a problem, BUT just after, it derailed on a turnout, I saw a spark and that was the end of the decoder. I have not had any decoders fry on me since. Sparks can occur at any time and white trafo or not, if they do, my understanding is that the decoders get fried. Why, I don't know.

One thing I have seen recently, and I do not know why, is that a digital loco, also brand new, used to run great on the analogue. Now when I try to run it in analogue (M tracks), sometimes it slows down without an apparent reason and then picks up speed. In digital, it runs perfectly.

I don't know if I was of any real help, but perhaps the best advice is still Mike's: Why take the risk? Get a white trafo, preferably new. Or, even better, keep the analogue with the analogue and the digital with the digital. This way you do not need to buy a new/used white trafo and any problems will not be due to the trafo.

BigGrin



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Offline SteamNut  
#6 Posted : 13 April 2015 05:34:52(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
There is a lot of evidence of electrocution from using old transformers but I never came across anyone that damaged a lok by using the reverse mode. The white transformers also have to send a higher voltage to activate the reverse mode. I do plan to retire my older ones in the next year or two but I am more worried about the condition of the insulation on the windings. Most likely in the future the reverse feature will be done electronically and not depend on sending a higher current to activate it.
Offline H0  
#7 Posted : 13 April 2015 08:13:24(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: baggio Go to Quoted Post
If you must run expensive digital locos in analogue, buy either a brand new white trafo or a used one where you know for a fact that what is inside is in excellent conditions.
The not so old transformers do not have a security risk coming from brittle insulation - and the reversing voltage can be measured (without opening it).

I wrote it before: I assume that a blue transformer made for 240 V can still produce excessive reversing voltages when used with 230 V (I don't have a transformer for 240 V so I cannot test it). There is no risk that the reversing voltage may be too low in that case.
The risk for decoders is slightly higher if the transformer was made for a lower voltage (110 V trafo on 120 V network or 220 V trafo on 230 V network).

Transformers may only be opened by qualified personnel. When you open it yourself you know for sure that you must not use it any more (unless your qualified to do so).
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline mike c  
#8 Posted : 13 April 2015 20:57:33(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 7,880
Location: Montreal, QC
I frequently encountered situations with my 1960s locomotives where the locomotive would occasionally shoot off at top speed instead of reversing. This happened more often if there was a large voltage drain on the transformer (e.g. a fully lighted train). On at least one or two occasions, this resulted in a collision or in a locomotive leaving the rails.
With digital locomotives, the voltage surge trips signals the decoder to reverse the locomotive direction. A surge that is lower than the trip voltage will not trip the reverse command, but it may damage other parts of the decoder. A surge that is too high might burn out the part of the decoder that receives the AC voltage.

The new decoders convert AC to DC to power the motors and a short that involves AC power (or any power for that matter) being fed into the output terminals of the decoder can very easily fry the decoder.

You have to be more careful with digital equipment. I would recommend that you connect your transformers to a power bar with a main kill switch so that you can shut off power in the event of a derailment or accident (especially if operating digital loks on an analog network).

Regards

Mike C
Offline SteamNut  
#9 Posted : 14 April 2015 02:17:24(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
One switch shuts all power to the layout and there is a separate circuit to the main panel and a dedicated circuit breaker for it. I should look for a surge protection if lighting hits the house which has happened in the past with only minor damage.
Offline cookee_nz  
#10 Posted : 16 April 2015 10:50:18(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,949
Location: Paremata, Wellington
Originally Posted by: SteamNut Go to Quoted Post
There is a lot of evidence of electrocution from using old transformers but I never came across anyone that damaged a lok by using the reverse mode. The white transformers also have to send a higher voltage to activate the reverse mode. I do plan to retire my older ones in the next year or two but I am more worried about the condition of the insulation on the windings. Most likely in the future the reverse feature will be done electronically and not depend on sending a higher current to activate it.


There is little risk from the internal windings, they are solid copper, coated in lacquer and I've not yet seen one deteriorate in any way, apart from friction wear at the contact point of the control knob wiper.

Much much more risky is the power cord that feeds the Trafo which has been covered in this topic....

https://www.marklin-users.net/forum/yaf_postst25901_Older-Metal-Transformer-Danger.aspx

Regards

Cookee
Cookee
Wellington
NZ image
Offline witzlerh  
#11 Posted : 16 April 2015 14:07:04(UTC)
witzlerh

Canada   
Joined: 25/09/2010(UTC)
Posts: 417
Location: Sherwood Park, AB, Canada
My grandpa showed me how to adjust the spring on the auto reverser. Too strong of a spring would mean a longer pulse required and the more uneven directional switching. ( easy to reverse, hard to go forward ).

As I am all digital now, I have not done it for years but did run across it described in the old Marklin maintenance book.

If you have too much power drain such as many lit coaches and accessories, the voltage drops too, requiring you to adjust the spring to weaken it. Too weak so a spring would mean a reverse happening at full throttle. The trick is finding the balance.

The reverser mechanism is electromechanical. Perhaps there is some gunk that is slowing the mechanical portion.

Take the body off the lok and observe the reverser operation.

Edited by user 16 April 2015 17:32:38(UTC)  | Reason: Clarification

Harald
CS2 DB & Canadian Era 3-6
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Offline MS 800  
#12 Posted : 19 April 2015 23:06:07(UTC)
MS 800

Germany   
Joined: 31/03/2014(UTC)
Posts: 36
Location: Ostalb, Württemberg
Hi, all,

I agree that a less than 5% of an up or down change in mains voltage in the sixties could easily be witnessed on a single day depending on the actual power consumption. Nowadays the power suppliers have learned a lot and are adjusting mains voltage according to the consumption they now can forecast rather exactly. Also, the consumption of the own layout, the total power of the transformers provided for the different current circuits and the number and distance of points where the voltage is fed into the rails certainly adds much more to the problems encountered than do the comparatively small voltage variations of the mains. The output voltage that is a littler higher ow lower now than it was, is easily adjusted as mentioned several times already following the description in the manual of any loco with the gold old mechanic solenoid switch.

Another problem, however, is the variation due to production tolerances of the old blue transformers that certainly was higher than it was with the newer grey ones. A member of a MRR forum here in Germany has performed some own measurements with a couple of different transformers and has measured voltages from the nominal 24VAC up to 31VAC for the switching impulse with the blue transformers he cound access, not depending on the type of model. The grey ones show much less variation in this respect, although they also do.

An aspect with the old transformers that has not yet been discussed here, is the issue of safety. All insulation materials, be it lacquer, rubber or any other kind of plastics, do age with time, eventually becoming cracked and brittle. On the mains cable this can easily be detected by the naked eye, but inside the blue steel case of the transformer the quality of the insulation can only be checked by measuring equipment. Thus, when you buy one of the old transformers off a MRR used items sale or off ebay, or íf one of your old transformers has witnessed a shock, e.g. by falling down to the floor, you can never be sure as to the actual state of the internal insulation means of the primary circuit. So go and have it checked by your electrician before using the transofrmer on your layout. A broken insulation not only places the hazard of an electric shock to your engines, but also to yourself.

Having done this, you can use any of those transformers safely. Still, if you do not want to run your engines with the risk of frying their decoders by high reverse impulse voltages, you can still use them for other circuits on your layouts, like powering the magnetic solenoid drives of signals or turnouts or any other articles or motors less "electronic" than the locos, or even lighting. For the latter, even the adjustable voltage of the original traction circuit (marked red) can be used. It adds a lot to the romantic look of a layout - and even more to the lives of the bulbs - if they are not all operated at the nominal 16VAC (which in most cases makes them burn too bright anyway), but some at 12, some at 10 and maybe even some at 8 volts.

Best regards

MS 800
When we were kids we enjoyed our tinplate trains rattling over tinplate tracks - nowadays they're in need of sound decoders.
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Offline H0  
#13 Posted : 21 April 2015 08:10:16(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: SteamNut Go to Quoted Post
I understand the risks using old transformers but has anyone damaged their loks when going in reverse when using them?
Coming back to the original question: I just read another "confession" on facebook from someone who damaged loco decoders with old transformers.
I have no doubt that the risk is real.
Mechanical reverse units may need adjustment when switching from old transformers (some have 31 V reversing voltage) to new transformers (around 25 V reversing voltage).
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
Offline SteamNut  
#14 Posted : 21 April 2015 12:54:19(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
Thank-you all for the replies. On my layout I have six transformers of which four are the old blue transformer dating as far back to 1967. All were purchased new at the time and never really used for 20 years till I made my present layout. This morning I measured the voltage and came up with 16.8 with a 26.7 reverse pulse. So far in 15 years I have not any problems with any digital loks on my analog layout but as I said previously I will retire my older ones in the near future. I suspect if anyone damaged a decoder from a transformer it was due to a prolonged reverse pulse or the loks were not fully stopped (user error). At least what I have read in this form decoders gave out due to other reasons other than the transformer.
Offline RayF  
#15 Posted : 21 April 2015 13:15:34(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,838
Location: Gibraltar, Europe
I only ever had one decoder go faulty in analogue operation, and this was an older 6090 type which blew one of its output transistors. Suddenly one day it only ran in one direction, and when I investigated I found one of the transistors was open circuit. I replaced the decoder with a 60902 decoder I bought off a dealer and it fixed the problem.

From what I have managed to learn over the years the older decoders, 6080, 6090, 6090x, 6603, 6603x types, were not as sensitive to high voltages as the newer programmable types. When I became aware of this issue I stopped using my old blue transformer and bought a cheap starter set just for its white transformer. I also got a loco, three wagons, and a quantity of track as a bonus! Since then I only use the old transformer as a fixed power supply for testing lights and accessories, or for testing old analogue locos.

To use this old transformer safely it was necessary for me to open it up and change the power cord, which was severely degraded inside the case. I have not measured the windings themselves but they seem to be in good condition. Nevertheless I keep a close eye on this transformer whenever I use it, which almost never nowadays.

Ray
Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
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